1. Field of the Invention
The present invention relates to a printed circuit board, e.g. for use in a camera, and a method for attaching a movable switch to the printed circuit board by the use of an improved soldering pattern.
2. Prior Art
A lens-fitted photographic film unit preloaded with a photographic film has a printed circuit board. The printed circuit board has electrical elements such as a synchro switch consisting of movable synchro contacts, a capacitor, a resistance and the like which are attached thereto such that all are soldered to lead lines formed on the printed circuit board. More particularly, the capacitor, the resistance and the like are attached to the lead lines by means of dip soldering. In this dip soldering, melted solder in a vessel also sticks to soldering land portions of the lead lines where the synchro contacts are to be soldered. Thereafter, a holder for holding the synchro contacts is attached to the printed circuit board such that each end of the synchro contacts is positioned on a respective end of the soldering land portions. Then the synchro contacts are soldered with a soldering iron.
When an exposure opening of the film unit is fully opened, the synchro contacts must be brought reliably into contact with each other by contact with a portion of a shutter blade in order to emit a flash of light for flash photography. Therefore, it is necessary to position the synchro contacts relative to the shutter blade with precision.
However, as the solder sticks to the soldering land portions in a swollen condition during the above-mentioned dip soldering, it is difficult to position the synchro contacts in contact with the middle portions of the soldering land portions, which are the only precise positions for the synchro contacts. Furthermore, there is a danger that the synchro contacts may be soldered obliquely with respect to the printed circuit board, which prevents accurate positioning of the synchro contacts relative to the shutter blade.